Semiconductor module

Abstract

Provided is a semiconductor module comprising a power semiconductor chip, a base, an insulating substrate bonded to the base, a semiconductor chip bonded to the insulating substrate, and a case adhered to the base by means of an adhesive. The semiconductor module has a low variability but a high assembly quality and reliability enabling a decrease in stress between the case and an adhered portion of the base. The base includes a plate-like first material, and a second material coating the first material and having a linear coefficient of expansion greater than that of the first material. The case covers at least part of a side surface of the base and is adhered to the base at least on an upper surface of the base by means of the adhesive, and a linear expansion coefficient of the case is larger than the linear expansion coefficient of the first material.

The invention claimed is: 
     
         1 . A semiconductor module comprising:
 a base;   an insulation substrate bonded to the base;   a semiconductor chip bonded to the insulation substrate; and   a case adhering to the base with an adhesive material, wherein   the base includes a plate-shaped first material and a second material covering the first material and having a linear expansion coefficient larger than a linear expansion coefficient of the first material,   in a case where the base is viewed in a plan view, the second material has first regions arranged at corner portions of the base and a second region arranged at an outer peripheral portion of the base and having a width narrower than a width of each of the first regions,   the case covers at least a part of a side surface of the base and adheres to the base, with the adhesive material, at least on an upper surface of the base, and a linear expansion coefficient of the case is larger than the linear expansion coefficient of the first material,   when a length from a center of a side of the base to an end portion of the base is L1, and a length from the center of the side of the base to a boundary between the first region and the second region is L2, L1−L2 is larger than a plate thickness of the base, and   L3≥L2 or L2−L3≥L1−L2 is satisfied in a case where a length from the center of the side of the base to an end portion on a corner portion side of the base of the adhesive material which adheres the case to the base on the side surface of the base is L3, and L3=0 in a case where there is no adhesive material on the side surface of the base.   
     
     
         2 . The semiconductor module according to  claim 1 , wherein
 a short side of the base satisfies L3≥L2, and   a long side of the base satisfies L2−L3≥L1−L2.   
     
     
         3 . The semiconductor module according to  claim 1 , wherein
 the first material is AlSiC, and   the second material is Al.   
     
     
         4 . The semiconductor module according to  claim 1 , wherein
 a length from the center of the side of the base to an end portion of the case facing the side surface of the base is the same as L3.   
     
     
         5 . The semiconductor module according to  claim 1 , wherein
 in the case where the base is viewed in a plan view, the first regions are arranged apart from one another at the corner portions of the base and a position other than the corner portions of the base.   
     
     
         6 . The semiconductor module according to  claim 5 , wherein
 the first regions are arranged to be spaced apart from one another at four corner portions of the base and in vicinity of centers of two long sides of the base, and   the case facing the side surface of the base is divided into two and arranged with the first region arranged in vicinity of each center of the two long sides interposed therebetween, in a long side direction of the base.   
     
     
         7 . The semiconductor module according to  claim 1 , wherein
 the L3=0, and there is no adhesive material between the base and the case on the side surface of the base, and   the case adheres to the base, with the adhesive material, on the upper surface of the base.   
     
     
         8 . The semiconductor module according to  claim 1 , wherein
 the case has a protruding portion facing a side surface of the base with the adhesive material interposed therebetween, and   the protruding portion is provided to cover at least a part of the side surface of the base.   
     
     
         9 . The semiconductor module according to  claim 3 , wherein
 a material of the case is PBT or PPS.   
     
     
         10 . The semiconductor module according to  claim 1 , wherein
 the semiconductor chip is a semiconductor chip on which an IGBT is mounted.